package xzr.Test3;
import java.util.Scanner;

class UserExistException extends Throwable {
    public String user;

    public UserExistException() {
        this.user = user;
    }

    @Override
    public String toString() {
        return
                "不存在'" + user + '\'' +
                '}';
    }
}


public class Test3 {
    public static void regist(String user) throws UserExistException {
        if (user.equals("123")) {
            throw new UserExistException();
        }
    }

    public static void main(String[] args) throws UserExistException {
        Scanner s = new Scanner(System.in);
        String n = s.nextLine();
        regist(n);

    }
}
